摘要：
For a positive integer N , the digit sum of N is defined as the sum of N itself and its digits. When M is the digitsum of N , we call N a generator of 阅读全文
摘要：
An organic compound is any member of a large class of chemical compounds whose molecules contain carbon. The molar mass of an organic compound is the 阅读全文
摘要：
You have devised a new encryption technique which encodes a message by inserting between its characters randomly generated strings in a clever way. Be 阅读全文